Reentry catheters and methods for traversing chronic total occlusions

ABSTRACT

A reentry catheter for crossing a vascular occlusion includes an elongate flexible tubular body, having a proximal end, a distal end and at least one lumen extending there through. A reentry zone on the tubular body includes at least two and preferably three sets of opposing pairs of axially spaced exit apertures in communication with the lumen. The apertures are rotationally offset from each other and aligned in a spiral pattern around the tubular body. A method of crossing a chronic total occlusion includes the steps of advancing the reentry catheter across the occlusion via a channel formed in the subintimal space, and advancing a guidewire via a selected exit port into the native lumen distally of the occlusion. The catheter may be removed, leaving the guidewire across the occlusion to guide further interventional devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/838,841, filed Apr. 2, 2020, which claims priority to U.S.Provisional Patent Application No. 62/830,199, filed Apr. 5, 2019, andto U.S. Provisional Patent Application No. 62/907,299, filed Sep. 27,2019, the entire contents of each of which is incorporated herein byreference in their entireties.

BACKGROUND OF THE INVENTION

An interventional guide wire or other interventional device is oftenused in medical procedures that attempt to establish a pathway through aheavily stenosed or chronically occluded vessel. A chronically occludedvessel is referred to as containing a chronic total occlusion or CTO.During these procedures, the guide wire or device can only be ofclinical benefit to establish vessel patency if it is advanced distallyinto the vessel true lumen.

One technique for restoring patency across a CTO involves advancing aguide wire through the intimal layer of the vessel wall and into thesubintimal plane or space, where it can be further advanced distallybeyond the CTO. Once in this sub-intimal plane beyond the CTO, itbecomes difficult to navigate the guide wire or device back through thesubintimal tissue layer to re-gain access into the vessel true lumen,sometimes referred to as a “reentry” into the vessel lumen from thesub-intimal space distally of the CTO. The layer of tissue thatseparates the vessel true lumen from the subintimal plane is typicallyin the range from 100 to 500 micrometers thick for vessels in thediameter range from 2 mm to 4 mm, and from 100 to 3000 microns thick, inthe largest vessels of the body.

A variety of catheters have been proposed for reentry around a CTO. Oneis described and shown in U.S. Pat. No. 6,231,546. In this system, there-entry catheter requires the operator to rotate a catheter shaft whileobserving a radiopaque marker on the catheter shaft to ensure that aside or lateral port is aimed at the true lumen of the blood vessel.Once the marker indicates the correct orientation of the lateral port, acannula is extended through the lateral port in order to penetratethrough the intimal layer of the blood vessel. It is believed that onedrawback of this system is the requirement to rotate the catheter to thecorrect position while under fluoroscopic imaging otherwise an incorrectorientation of the cannula could cause failure to reenter the parentlumen and potentially cause damage to the vessel.

Another system is described and illustrated in US Patent ApplicationPublication 2013/0072957. In this publication, a balloon is used toorient the cannula into the proper orientation for re-entry into thetrue vessel lumen. To achieve this, the catheter utilizes anasymmetrical catheter lumen for the cannula. It is believed that thissystem also suffers from a similar drawback in that the lateral port ofthe cannula must be oriented in the correct direction towards the truelumen while under fluoroscopy. This is to ensure that the cannula doesnot penetrate away from the true lumen, which could lead to internalhemorrhaging.

Despite the foregoing and other efforts in the prior art, there remainsa need for an improved reentry catheter and method for traversing totalchronic occlusions.

SUMMARY OF THE INVENTION

Disclosed is a reentry catheter for crossing a vascular occlusion. Thecatheter includes an elongate flexible tubular body, having a proximalend, a distal end and at least one lumen extending there through. Areentry zone on the tubular body includes at least two and preferably atleast three or five or more exit apertures in communication with thelumen, the apertures rotationally offset from each other by at leastabout 15 degrees and aligned in a spiral pattern around the tubularbody. In one implementation, three pairs of opposing apertures areprovided.

A method of crossing a chronic total occlusion includes the steps ofadvancing a guidewire from a vascular lumen through the intima, into asubintimal space and distally beyond the occlusion. A reentry catheteris advanced over the guidewire and beyond the occlusion, such that atleast one of a plurality of spirally aligned exit ports on the reentrycatheter is rotationally aligned with the lumen. The guidewire isadvanced through the at least one exit port to cross the intima andreenter the lumen. The reentry catheter may be removed, and a ballooncatheter may be advanced over the wire and the balloon expanded in thesubintimal space to create a neolumen that permits perfusion across theocclusion. A stent may be expanded in the neolumen to maintain patencyacross the occlusion.

There is provided, in accordance with another aspect of the presentinvention, a re-entry catheter for crossing a vascular occlusion. Thecatheter comprises an elongate flexible tubular body, having a proximalend, a distal end and at least one lumen extending there through. Areentry zone is defined on the tubular body, comprising at least twoexit apertures in communication with the lumen, the aperturesrotationally offset from each other by at least about 5 degrees, and thereentry zone is positioned within about 20 cm of the distal end of thetubular body.

The re-entry zone may be comprised of at least three apertures, or atleast five apertures, arranged in a spiral configuration around thetubular body. At least one aperture may have a noncircular configurationand at least one aperture may have a major axis in parallel to alongitudinal axis of the tubular body, and a minor, transverse axis. Atleast one aperture has a minor axis diameter of at least about 0.025 mm.

In accordance with another aspect of the present invention, there isprovided a method of crossing a chronic total occlusion. The methodcomprises the steps of advancing a guidewire from a vascular lumenthrough the intima, into a subintimal space and distally beyond theocclusion. A reentry catheter is advanced over the guidewire and beyondthe occlusion, such that at least one of a plurality of exit ports onthe reentry catheter is rotationally aligned with the lumen. Theguidewire is advanced through the at least one exit port to cross theintima and reenter the lumen.

The method may additionally comprise the step of applying vacuum to thecentral lumen or secondary lumen to draw adjacent tissue against one ormore side ports. Vacuum may also be used to aspirate hematoma or otherembolic material into one or more side ports, and/or the distalguidewire opening into the central lumen.

The method may further comprise the step of proximally retracting thecatheter, leaving the guidewire extending into the lumen distally of theocclusion. A balloon catheter may be advanced over the wire and theballoon expanded in the subintimal space. A stent may be expanded in thesubintimal space to maintain patency of a neolumen that permitsperfusion across the occlusion.

In accordance with a further aspect of the present invention, there isprovided a reentry catheter for crossing a vascular occlusion,comprising an elongate flexible tubular body, having a proximal end, adistal end and at least one lumen extending there through; and a reentryzone on the tubular body, comprising at least three opposing pairs ofside wall exit apertures in communication with the lumen, each opposingpair of apertures rotationally offset from an adjacent opposing pair ofapertures.

The reentry catheter may additionally comprise a reinforcing ringsurrounding each aperture. The catheter may be provided with sixreinforcing rings, one for each aperture, and the reinforcing rings maybe connected together by a frame in the side wall which may be in theform of a tubular support. The reinforcing rings may comprise aradiopaque material. The frame may comprise a helical strut extendingbetween a first and second axially spaced apart opposing pairs of sidewall exit apertures.

The catheter may further comprise an inflatable balloon on the tubularbody, in communication with a second, inflation lumen extending axiallythrough the tubular body. A guidewire lumen may extend axially throughthe tubular body between a proximal port and a distal port, and theproximal port may be spaced distally apart from the proximal end or atthe proximal end of the tubular body. The proximal port is within about20 cm of the distal end of the tubular body.

There is also provided an intravascular catheter with fluoroscopicallyvisible indicium of rotational orientation. The catheter comprises anelongate flexible tubular body, having a proximal end, a distal end anda tubular side wall defining at least one lumen extending there through;and first and second opposing pairs of radiopaque rings in the sidewall, spaced axially apart from each other; wherein a first transverseaxis extending through the first pair of rings is rotationally offsetfrom a second transverse axis extending through the second pair ofrings.

The intravascular catheter may further comprise an aperture in the sidewall through each ring. The catheter may further comprise a frameconnecting the rings, which may comprise one or more struts configuredto provide a flexible hinge. At least a portion of the frame in betweenthe first and second opposing pairs of rings in one implementationcomprises a spring hinge in the form of at least one helical strut.

In accordance with a further aspect of the present invention, there isprovided a subassembly for integration into the wall of a catheter. Thesubassembly comprises a tubular body having a plurality of apertureportions and intervening hinge portions. Each aperture portion includesa first and a second aperture carried on opposing sides of the tubularbody. A first axis extending transversely through the tubular body andthe first and second apertures of a first aperture portion isrotationally offset from a second axis extending transversely throughthe tubular body and the first and second apertures of a second apertureportion.

The hinge portion may comprise a helical strut. The aperture portionsand intervening hinge portions may be parts of a unitary body which maybe laser cut from a tube. Each aperture may be formed within an eyeletseparated from an adjacent eyelet by a hinge portion.

An aperture may have a minor axis and a transverse major axis having alength of at least about 150% of the length of the minor axis. Thesubassembly body may have a wall thickness of no more than about 0.05inches, and in some implementations no more than about 0.004 inches.

The subassembly may have at least three pairs of opposing apertures withintervening hinge portions between each aperture pair. A first hingeportion may comprise a helical strut having a first pitch and a secondhinge portion spaced apart from the first hinge portion by an aperturepair portion, may have a helical strut having a second, different pitch.

Further features and advantages of the invention will become apparent tothose of skill in the art from the following description taken togetherwith the associated drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a reentry catheter in accordancewith the present invention.

FIG. 2 shows the anatomy of a coronary artery.

FIG. 3A shows a guidewire entering a subintimal space to cross anocclusion.

FIG. 3B shows a reentry catheter tracking over the guidewire and throughthe subintimal space.

FIG. 3C shows the guidewire passing out of a selected exit port and backthrough the intima and into the true lumen distal to the occlusion.

FIG. 3D shows proximal retraction of the reentry catheter while leavingthe guidewire in position across the occlusion.

FIG. 3E shows a balloon catheter carrying a balloon expandable stentpositioned across the occlusion via the subintimal space.

FIG. 3F shows the catheter removed, leaving the stent expanded tosupport a neo lumen to permit perfusion across the occlusion in thenative lumen.

FIG. 4A shows a reentry catheter with a guidewire exiting a first exitport at a first rotational orientation.

FIG. 4B shows a reentry catheter with a guidewire exiting a second exitport at a second rotational orientation.

FIGS. 5A and 5B show geometric aspects of the exit ports.

FIGS. 6A-6C show various exit port details.

FIGS. 7A-7B show lateral exit of a guide wire through an exit port withan exit ramp.

FIG. 8 shows a biased deflection guide for directing a guidewire towardthe native lumen.

FIG. 9 shows a reentry catheter with a reinforced reentry zone.

FIG. 10A is a side elevational view of a reinforcing insert forsupporting the reentry zone.

FIG. 10B is a side elevational cross section through the catheter wallat the transition between the braid and the proximal end of the reentryzone support.

FIG. 10C is a perspective view of the cross section shown in FIG. 10B.

FIG. 10D is a perspective cross sectional view of the transition betweenthe distal end of the reentry support and the catheter tip.

FIG. 10E is a perspective cross sectional view of an eyelet formed bythe reentry support, having a radiopaque overlay surrounding theaperture.

FIGS. 11A, 11B and 11C show three rotational orientations of a reentryzone support.

FIG. 11D is an exploded side elevational view of the reentry zonesupport of FIG. 11A.

FIG. 11E is a side elevational view of the support of FIG. 111A, in acurved configuration.

FIG. 12 is a cross sectional perspective view of a catheter shaftportion having separate guide wire and aspiration lumen.

FIG. 13 is a perspective view of a reentry zone having a mix of reentryports and tissue stabilizing aspiration ports.

FIG. 14 illustrates different fluoroscopic visualization options.

FIG. 15 is a schematic illustration of a reentry catheter distal endhaving an active deflection mechanism.

FIG. 16 shows a steerable reentry catheter with integrated handle.

FIG. 17 schematically illustrates reentry zones in combination with aguidewire steering insert.

FIG. 18 is a schematic illustration of a reentry catheter distal endhaving one configuration of a rapid exchange lumen.

FIG. 19 is a side elevational view of the integrated handle.

FIG. 20 illustrates the use of the reentry catheter to accomplish adelivery into the subintimal space.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 , there is disclosed a catheter 10 in accordancewith one aspect of the present invention. Although primarily describedin the context of a reentry catheter with a single central lumen,catheters of the present invention can readily be modified toincorporate additional structures, such as permanent or removable columnstrength enhancing mandrels, two or more lumen such as to permit drug orirrigant infusion or to supply inflation media to an inflatable balloon,or combinations of these features, as will be readily apparent to one ofskill in the art in view of the disclosure herein.

The catheters disclosed herein may readily be adapted for use throughoutthe body wherever it may be desirable to create an extravascular accessor a neo lumen, such as to traverse a CTO or otherwise exit and reenterthe lumen. For example, catheter shafts in accordance with the presentinvention may be dimensioned for use throughout the coronary andperipheral vasculature, the gastrointestinal tract, the urethra,ureters, Fallopian tubes and other lumens and potential lumens, as well.

The catheter 10 generally comprises an elongate tubular body 16extending between a proximal end 12 and a distal functional end 14. Thelength of the tubular body 16 depends upon the desired application. Forexample, lengths in the area of from about 120 cm to about 160 cm ormore are typical for use in femoral access percutaneous transluminalcoronary applications. Intracranial or other applications may call for adifferent catheter shaft length depending upon the vascular access site,as will be understood in the art.

The proximal end 12 of catheter 10 is additionally provided with amanifold 18 having one or more access ports as is known in the art.Generally, manifold 18 is provided with a guidewire port 20 in anover-the-wire construction, and an optional side port 22 depending uponthe desired functionality. Additional access ports may be provided asneeded, depending upon the functional capabilities of the catheter.Manifold 18 may be injection molded from any of a variety of medicalgrade plastics, or formed in accordance with other techniques known inthe art.

The tubular body 16 is provided with a reentry zone 40, extendingbetween a proximal exit port 42 and a distal exit port 44, configured topermit exit of a guidewire therethrough. Preferably at least three orfive or seven or more exit ports or port pairs are provided, arrangedcircumferentially offset from each other so that regardless of therotational orientation of the catheter in the vessel, at least one exitport will be facing the direction of the true vessel lumen. The exitports may be arranged in a spiral, with axially adjacent ports rotatedfrom each other about the longitudinal axis of the catheter within therange of from about 5 degrees and 90 degrees, preferably between about10 degrees and 60 degrees, and in some embodiments between about 15degrees and 35 degrees.

In an axial direction, adjacent ports may be spaced apart by a distancewithin the range of from about 2 mm to about 4 mm or about 5 mm andabout 15 mm. Side ports define a reentry zone 40 having an axial lengthfrom the proximal most port 42 to the distal most port 44 of at leastabout 2 mm and generally less than about 20 mm; in many implementationsbetween about 4 mm and 15 mm. The side ports define a spiral thatextends at least about 45 or 90 degrees around the catheter side wallbut typically no more than about 360 degrees and in certain embodimentswithin the range of from about 270 degrees and 450 degrees.

Referring to FIG. 2 the coronary artery walls are made up of three mainlayers. The intima is the innermost layer consisting of a single layerof endothelial cells. The fibromuscualar media includes nonstriatedmyocytes. The adventitia is the outermost layer composed of collagen andelastin.

The intima layer can thicken considerably over time, occluding the bloodflow through the artery. A chronic total occlusion (CTO) is a completeblockage of the artery. The present invention relates to a method totreat a CTO by creating a new lumen in the subintimal space (between theadventitia and intima) in order to allow blood flow in the artery aroundthe occlusion.

Referring to FIG. 3A, a guidewire 50 is advanced through the arteriallumen 52 to the proximal side of an obstruction to be treated such as aCTO 54. Progress of the wire 50 may be impeded or deflected due to theCTO. If the guidewire cannot cross the lesion, the guidewire may bepassed distally beyond the lesion by way of an intentional dissection,and is advanced in a created subintimal channel between the intimal andmedial layers of the arterial wall. This allows the guidewire 50 tocross the CTO 54 via the subintimal space. A reentry catheter 10 is thenadvanced over the guide wire 50, following the guidewire from the nativearterial lumen, through the dissection and into the subintimal space.See FIG. 3B. The guidewire 50 may thereafter be retracted into the guidecatheter.

As seen in more detail in FIG. 3C, the reentry catheter 10 exits thenative lumen at a subintimal entry point 56, and travels distally withinthe subintimal space. The guide wire 50 may thereafter be advanceddistally within the reentry catheter 10 and rotated to find the exitport having the desired axial and rotational orientation to direct theguidewire 50 towards the native vascular lumen 52. The guidewire maythereafter be distally advanced to exit through the selected exit port58, distal of the lesion 54, for reentry into the native vascular lumen52 at guidewire reentry point 60.

Once the guidewire 50 has correctly reentered the lumen distally of theCTO, the reentry catheter 10 can be proximally retracted from thesubintimal space leaving the guidewire in position via the neo lumenacross the CTO. See FIG. 3D. The reentry catheter can thereafter bewithdrawn from the artery.

Any of a variety of procedures can be accomplished with the guidewire inposition across the CTO. For example, referring to FIG. 3E, a ballooncatheter 62 can be advanced over the guide wire 50 to position aninflatable balloon 64 in the subintimal space. Dilitation of the ballooncan open a flow channel to cross the CTO via the subintimal space. Theballoon may carry a balloon expandable stent 66 which can be expandedspanning the CTO to support the neo lumen against collapse followingremoval of the balloon as is understood in the art. Alternatively aself-expanding stent may be deployed across the CTO, preferablyfollowing a mechanical dilatation (e.g., balloon dilatation step).

Additional details of the catheter design may be seen with reference toFIGS. 4A-5A. A plurality of successive axially spaced exit ports 46 arearranged in a spiral such as a helix about the longitudinal axis of thecatheter. The guide wire 50 may have a pre-bent tip so that it is biasedlaterally against the inside diameter of the reentry catheter sidewall.The guide wire may be distally advanced and rotated to align, forexample, with distal most exit port 44 and advanced through that port.See FIG. 4A.

Alternatively, if the native arterial lumen is in a differentorientation relative to the reentry catheter 10, the guide wire can beaxially repositioned and rotated to align and exit via a seconddifferent exit port to reenter the arterial lumen at a differentorientation as seen in FIG. 4B.

Referring to FIGS. 1 and 5A, the proximal most port 42 and distal mostport 44 define reentry zone 40 along which a plurality of ports 46 willgenerally encompass at least about 270 and preferably about 360 degreesaround the circumference of the reentry catheter 10. Generally betweenabout 4 and 16 ports are provided with one embodiment between about sixand ten ports. A reentry zone 40 having eight ports aligned along a 360degree spiral results in 45 degrees of rotation between adjacent ports.Preferably, ports are arranged in sets of opposing pairs, as isdiscussed further below.

Referring to FIG. 5B, the ports will generally have a major axis 80extending longitudinally along the catheter and a minor, transverse axisextending circumferentially around the tubular body. The major axis willtypically be within about 15 degrees or 10 degrees or less from parallelwith the catheter longitudinal axis and may be about parallel to thelongitudinal axis as shown in FIG. 5B, or aligned with the spiral onwhich the ports reside.

The major axis 80 is generally longer than the minor axis 82, and may beat least about 150%, or 175% or 200% or more than the length of theminor axis 82. In some implementations of a reentry catheter, the minoraxis 82 is within the range of from about 0.012 inches to about 0.20inches; or about 0.014 inches to about 0.018 inches. The major axis 80is within the range of from about 0.024 inches to about 0.046 inches, orabout 0.030 inches to about 0.042 inches. In one example, the port isabout 0.016 by about 0.034 inches in a catheter having an OD of about0.038 inches. The minor axis of the port may be less than about half ofthe tubular body OD and over about half of the catheter body ID.

Preferably, the ID of the tubular catheter body is at least about 120%or 150% or 175% or 200% or more of the OD of the GW intended to be usedwith the catheter. In one implementation, a catheter having an ID ofabout 0.028 inches is intended for use with a 0.014 inch guide wire. Thedifference between the diameter of the guide wire and the ID of thecatheter is generally at least about 0.005 or about 0.010 or more, tofacilitate manipulation of the guidewire and directing the guidewiretowards a desired exit port.

In addition, the relatively large space between the guidewire and the IDof the catheter facilitates application of vacuum (e.g., up to about 29″Hg, or 20 mm Hg) while the guide wire is in position extending throughthe tubular body, which allows negative pressure applied to the centrallumen to produce suction at the exit ports for anchoring the catheter tothe adjacent tissue. Anchoring the reentry zone to adjacent tissue maybe desirable to stabilize the catheter and facilitate penetration duringthe step of puncturing tissue with the guidewire to reenter the vessellumen distally of the obstruction.

The exit ports 46 may be spaced apart axially by a distance within therange of from about 0.05 inches to about 0.25 inches or in someembodiments from about 0.08 inches to about 0.20 inches. Multi-sizedports can be provided, with a first set of guidewire exit ports and asecond set of smaller aspiration ports arrayed among the guidewireports. Multiple sizes of ports may also be utilized for infusion oftherapeutic agents.

A variety of port geometries and ramp geometries may be utilized tooptimize control over port selection and guidewire exit. Referring toFIG. 6A, the edge of the catheter wall at the distal end of a port 46may be provided with a ramped surface 84 configured to facilitate exitof the guidewire. Alternatively, a ramp surface 84 may be provided byforming a tab 86 that inclines radially inwardly in a proximal directioninto the lumen. A guidewire with a laterally biased tip can be rotatedand advanced until the tip enters the port assisted by the ramp 84 onthe sidewall or on a tab. See FIGS. 7A and 7B.

Deflection of the guidewire may also be facilitated by an intermediatedeflection element such a deflection guide 88. See FIG. 8 . Thedeflection guide 88 may comprise a shape memory (e.g., Nitinol) tube 90that is preset to an angle upon proximal retraction of or distal advancefrom of a restraint.

Referring to FIG. 9 , there is illustrated a reentry catheter 10including a reentry zone support 92 extending throughout the reentryzone 40. The support 92 includes a tubular body 94 extending between aproximal end 96 and a distal end 98 and which carries a plurality ofexit ports 46 spaced apart by a plurality of intervening flexible links47. Additional detail is described in connection with FIGS. 10A-10E.

Extending proximally from the support 92 is a kink resistance and torquetransmission feature such as a braided tubular sidewall component 186.Braid 186 may be a stainless steel braid having between about 12 and 20filaments, and in one implementation 16 rectangular filaments having awidth that is at least about 3× or 4× the thickness. The braid mayoverlay a coil layer 188, which in one implementation is a four filarcoil of 0.001″ tungsten wire at about 0.008″ pitch. The braid 186overlaps the proximal end of the support 92, but in the illustratedimplementation the distal end of the coil 188 is spaced proximally apartfrom the proximal end of the support 92.

At least a first eyelet frame 100 comprising an annular strut 102encircles a guidewire exit port or aperture 104 on a first side of thetubular body 94. In the illustrated embodiment, the first eyelet frame100 is spaced apart from the proximal end 96 by a first flexible link106 in the form of an elongated helical strut 108. Proximal end 96 isadditionally provided with a plurality of anchors such as at least aboutfour or six or eight or more proximally extending ribs 110, forfacilitating attachment to the outer surface of an underlying catheterbody component such as a woven or braided reinforcement layer as shownin FIG. 10C.

A second eyelet frame 112 in the form of a second annular strut 114defines a second aperture 116. Second eyelet frame 112 is space distallyapart from the first eyelet frame 100 by a second flexible link 118 inthe form of a second helical strut 120. The total number of apertures ina reentry zone on a particular reentry catheter can be varied dependingupon the desired clinical performance, as has been discussed elsewherehere in.

Referring to FIG. 10D, the distal end of the reentry support 92 isprovided with at least about four or six or eight or more tip anchorssuch as axially extending ribs 190. Ribs 190 may be provided with acircumferential segment 192 to create an interference fit when embeddedin the polymer of the tip 194, which may comprise 35D PEBAX. As shown inFIG. 10E, selected portions of the reentry support may be provided witha radiopaque marker such as a radiopaque coating layer. In theillustrated embodiment, the annular struts or eyelets that define theports are provided with a layer of radiopaque material such as a Pt/Iralloy, allowing an opposing port pair to appear as an oval aperture whenaligned with the viewing axis.

As seen in FIGS. 11A-C, a six port implementation is shown in which eachaperture on a first side of the tubular body is paired with a secondopposing aperture on the opposite side of the tubular body to formfirst, second and third aperture pairs 130, 132 and 134. A support 92viewed from the perspective of FIG. 11A along an axis that extends at aperpendicular through each of the first and second windows 104A and 104Bof the first aperture pair 130 appears under fluoroscopic visualizationas a dark ring surrounding an opening, or an “O” or other indicium of afirst rotational orientation.

The support 92 as shown in FIG. 11B has been rotated about itslongitudinal axis by 60° compared to FIG. 11A. Viewed from the sameviewing angle, the first aperture pair 130 is no longer aligned with theviewing axis so the window 104A has visually disappeared. Instead asidewall of the tubular body becomes opaque such as in the form of an“X” or other indicium of a second rotational orientation. The first andthird aperture pairs 130, 134 appear as an X or other indicium of nonalignment. A further rotation of the support through an additional 60degrees produces the view shown in FIG. 11C, in which the visualized “O”has moved to the third aperture pair 134.

Thus, the white “O” will progress along the length of the support fromexit port pair to next adjacent exit port pair, as a function ofrotational orientation. In this manner, the clinician can determine therotational orientation of the distal end of the catheter underfluoroscopic visualization by tracking the location of the O and the X'srelative to catheter rotation. This facilitates rotational alignment ofthe catheter relative to the true lumen, and selection of theappropriate exit port for launching the guidewire through the selectedport and in the direction of the true lumen.

Referring to FIG. 11D, there is illustrated an exploded view of thedifferent functional components of the support. The components may beseparately formed and connected such as by welding, or the entireassembly may be cut from a single piece of tubestock such as by lasercutting, EDM or other techniques known in the art.

Trackability and pushability are catheter characteristics that rely onthe ability for the distal end of the catheter to push through thetortuous anatomy of the cardiac arteries. The consistency of the bendingmoments throughout the catheter shaft have significant impact on theseuse characteristics. The illustrated support insert comprises 9 discreteregions, labelled 1-9 in FIG. 11D.

1. The proximal end is provided with a plurality of engagementstructures such as at least two or four or six or more axially extendingfingers designed to overlap and intertwine with the braid and coilreinforcement of the shaft

2. First, proximal, single or dual start, first direction such asclockwise spring section. This proximal spring section has the highestrelative stiffness to account for the moment arm to the distal end ofthe catheter and enable the smooth, approximately constant radiuscurvature under lateral load, as seen in FIG. 11E. This section is atleast about 2× or 3× or preferably 4× stiffer than the distal end 9. Asillustrated, the spring section has 3 revolutions, 0.021″ pitch, 0.0045″width.

3. First proximal port. Annular frame is configured to define an oblongport and opposing aperture pair to provide differing visual presentationunder fluoroscopy indicative of rotational orientation. Dual exitlocations are approximately 180 degrees rotated.

4. 2nd spring region may have a counterclockwise rotation to enhancetorque response, and may also have a dual start. As illustrated, thesecond spring section has 4 revolutions, 0.014″ pitch, 0.0040″ width.

5. The middle port pair 132 is rotated 60 degrees from first port pair130. All other geometry of the three port pair frame segments are thesame.

6. The third spring region may have about 4 revolutions, 0.014″ pitch,0.0030″ width.

7. The distal port pair 134 is rotated 60 degrees from the middle portpair 132.

8. The fourth spring region may be provided with between about three and10 and in the illustrated embodiment six dual start revolutions, 0.0105″pitch, 0.0030″ width

9. The distal end is provided with a plurality of anchors configured formaximum surface area to allow embedded anchoring within the soft tipmaterial to intertwine with the metallic insert and increase tensilestrength.

Any of the pitch and width dimensions provided above can be varied by+/−5%, 10% 15%, or 20% depending upon the desired performance.

Reinforcement of the apertures can be accomplished with multiplecomponents that can articulate. Reinforcement may have spring likecomponents for inter-connection. Material may be polymeric or metallic.Material may be radiopaque. Reinforcement will be layered withinpolymeric tubing to create a laminate structure. Ports may be cutthrough the braided regions before or after lamination. Multiplematerials of construction may be used. Components may be welded togetherfor robustness. Ports can be singulated (discrete components) andpositioned in multiple orientations to optimize selection by theguidewire. Material may be polymeric or metallic. Ports can be singlesided. Ports can be dual sided as illustrated.

One aspect of the invention involves aspiration via the side ports tosecure adjacent tissue. Aspiration can be accomplished via the guidewireexit ports and/or separate aspiration ports.

For example, referring to FIG. 12 , there is illustrated a perspectivecross section through a catheter body segment 150, showing a guidewirelumen 152 in communication with at least one exit port 154, and aseparate aspiration lumen 156 in communication with at least oneaspiration port 158. In any of the embodiments disclosed herein, theaspiration lumen or guidewire lumen may also be used to infuse fluidswhich may include one or more drugs.

FIG. 13 illustrates a reentry catheter segment having relatively largerguidewire exit ports, and a plurality of smaller aspiration ports.Aspiration can be accomplished either via guidewire exit ports ordedicated aspiration ports. In either case, aspiration can reduce theblood volume in the neo lumen and or stabilize the wall of the neo lumen(intima) to facilitate puncture by the guidewire to facilitate reentryinto the native lumen.

Blood aspiration flow rates, pressure may be controlled via an externalvacuum source. Vacuum regulators may be provided to control flow rates,and absolute pressures. Guidwire Re-entry port design may also be usedto aspirate blood during access into subintimal space. The vacuum sourcewill be able to measure pressure differentials within the device. Thevacuum source may be design as a stand-alone system or connected to alab's vacuum source. Additionally, a pressure pump may be used as avacuum source. Vacuum can be applied in a multitude of modes that arecontrolled by surgeon or automated. Pulsatile for effective aspirationof hematoma, pulsatile to allow axial advancement while removinghematoma, high pressure or low pressure pulsatile vacuum can becontrolled by an automatic valve that pulses at a discrete or variablefrequency

FIG. 14 shows different visualization schemes that may be employed.Preferably, the distal tip has high radiopacity to facilitatevisualization. First and second marker bands are preferably positionedat the proximal and distal ends of the reentry zone. In oneimplementation, the reentry zone may be substantially radiolucent, andthe frame surrounding each exit port is radiopaque.

The catheter shaft may be steerable bi-directionally oruni-directionality. The catheter shaft may have the ability toaccumulate torque between the handle and the tip. The catheter may havethe ability to advance in a way that ‘taps’ to facilitate tracking—axialextension and compression. All of these characteristics are tofacilitate tracking through tortuous anatomy and facilitate traversingthe subintimal plane.

Referring to FIGS. 15 and 16 , there is illustrated a bidirectionallysteerable catheter 10. A proximal control 160 such as a rotatable wheelor axial slider is in communication with a distal steering zone 162 byat least one and, as illustrated, two pull wires 164, 166. Manipulationof the control 160 to proximally retract the pull wire 166 will deflectthe steering zone 162 in a first direction as illustrated. Proximalretraction of the second pull wire 164 will cause deflection of thesteering zone 162 in a second, opposite direction.

Referring to FIG. 17 , the design may optionally incorporate an internalsteerable guide sheath 170 between the guidewire and the catheter shaft.Guide sheath includes a guidewire lumen 172 which terminates distally ina ramped surface to direct a guidewire through a lateral guide wire port174. To prevent a physician from spinning a GW (trial and error) to getto a desired exit port, the sheath 170 will cover all holes except thedesired re-entry port which is aligned with sheath port 174. The usermay easily select the desired ports by localizing the ports underfluoroscopy and axially and rotationally adjusting the guide sheath toaim at the desired exit port.

Referring to FIG. 18 , a dual-lumen catheter shaft may be provided toallow for a Rapid Exchange catheter design. A first, reentry guidewiremay be advanced through the lumen accessed vial the proximal luer, and asecond, navigational guidewire may be advanced through the second, rapidexchange lumen. In this configuration, the proximal exit port for thesecond, rapid exchange lumen will be located on a side of the catheterdistally of the proximal luer, such as within about 40 cm or 30 cm or 20cm of the distal end of the catheter.

The first lumen may also be used for aspiration while the second lumenmay only be available for a guidewire. It may be desirable to isolateone or more lumens for aspiration, such as shown in FIG. 18 . Forexample a one-way valve may permit passing of a guidewire but also closewhen the guidewire is removed to facilitate aspiration via the otherlumen.

Referring to FIG. 19 , the integrated handle may be connected to a powersource (1) for therapeutic delivery while accessing the subintimalspace. Power sources may include, for example, radio frequencygenerators for RF ablation or cryoablation generators, and a RF or cryodelivery element may be carried by the distal end of the catheter or bya removable catheter insert depending upon the desired functionality.

The integrated handle may also be connected to a vacuum source (2) forblood aspiration to prevent hematoma as well as assisting with devicefixation within the subintimal space. The integrated device may includea vacuum accumulator within the handle that could interact with operatorcontrols.

The integrated handle and one or two or more lumen extending throughoutthe catheter may also be configured to be compatible with a variety ofcommonly used tools for CTO crossing procedures, including guidewires,guide liners to increase stiffness for increase pushability, drillingmicrocatheters to gain access to the subintimal space; dilation ballooncatheters; or infusion pumps for delivering therapeutic agents.

Referring to FIG. 20 , the catheter 10 provides the ability to accessthe subintimal space and achieve a variety of additional advantages suchas the ability to deliver drugs such as therapeutic agents to help healdissections, anticoagulants, or contrast, or monitor ECG signals. Inaddition, the catheter enables delivery of a variety of devices 180,such as customized implants or sensors.

It may be desirable to coat the outside surface of the guidewire and/orthe inside surface of the wall defining the guidewire lumen with alubricous coating to minimize friction as the catheter 10 is axiallymoved with respect to the guidewire. A variety of coatings may beutilized, such as Paralene, Teflon, silicone rubber,polyimide-polytetrafluoroethylene composite materials or others known inthe art and suitable depending upon the material of the guidewire orinner surface of the tubular wall.

In prior art intravascular catheters, the intended guidewire is normallyconfigured to substantially occupy the guidewire lumen, with a minimaltolerance necessary to avoid excessive friction. For example, a catheterhaving a 0.018″ ID guidewire lumen might be used with a 0.014″guidewire. The reentry guidewire of the present invention is preferablysubstantially smaller than the ID of the complementary lumen. Forexample, a 0.014″ guidewire may be used with a catheter 10 having a0.028″ lumen. In general, the guidewire will have a diameter that is nomore than about 80%, and preferably no more than about 70% or 60% of theID of the corresponding lumen. This provides an aspiration flow path inthe space between the guidewire and the lumen wall to enable aspirationof blood from the intraluminal space and anchoring of the catheteragainst adjacent tissue while the guidewire remains in place. Forexample, with a 0.014″ guidewire present and a maximum vacuum pressureof 20 mmHg, at least about 6 mL/Min, and preferably at least about 8mL/MIN or at least about 10 mL/min of saline or water or more isaspirated.

The catheters of the present invention may comprise any of a variety ofbiologically compatible polymeric resins having suitable characteristicswhen formed into the tubular catheter body segments. Exemplary materialsinclude polyvinyl chloride, polyethers, polyamides, polyethylenes,polyurethanes, copolymers thereof, and the like. Optionally, the tubularbody may further comprise other components, such as radiopaque fillers;colorants; reinforcing materials; reinforcement layers, such as braidsand helical reinforcement elements; or the like. In particular, thetubular body may be reinforced such as with an embedded coil or one ortwo or more braided tubular layers in order to enhance its columnstrength and torqueability while preferably limiting its wall thicknessand outside diameter. The tubular body 16 may be produced in accordancewith any of a variety of known techniques for manufacturinginterventional catheter bodies, such as by extrusion of appropriatebiocompatible polymeric materials.

Radiopaque markers may be provided at least at the distal end 25 and theproximal end of the reentry zone 40. One suitable radiopaque markercomprises a metal band which is fully embedded within the catheter wall.Suitable marker bands can be produced from a variety of materials,including platinum, gold, and tungsten/rhenium alloy.

In many applications, the tubular body 16 is provided with anapproximately circular cross-sectional configuration having an externaldiameter within the range of from about 0.025 inches to about 0.065inches. In accordance with one embodiment of the invention, the proximalsection of tubular body 16 has an external diameter of about 0.042inches (3.2 f) throughout most of its length. Alternatively, a generallyoval or flattened cross-sectional configuration can be provided in adistal zone, as well as other noncircular configurations, depending uponthe desired performance.

In a catheter intended for peripheral vascular applications, at leastthe proximal section of body 16 will typically have an outside diameterwithin the range of from about 0.039 inches to about 0.110 inches. Incoronary vascular applications, the proximal section of body 16 willtypically have an outside diameter within the range of from about 0.025inches to about 0.080 inches. The OD of the catheter may taper or stepto a smaller diameter or dimension in a distal zone.

Diameters outside of the preferred ranges may also be used, providedthat the functional consequences of the diameter are acceptable for theintended purpose of the catheter. For example, the lower limit of thediameter for any portion of tubular body 16 in a given application willbe a function of the number of fluid or other functional lumen containedin the catheter, together with the acceptable minimum performancecharacteristics.

For example, referring to FIG. 9 , a strain relief 182 may extend withinthe range of from about 25 mm to about 50 mm, or about 35 to about 40 mmfrom the proximal hub. The OD steps down from about 0.080″ to about0.041″ (less than about 75% or 65% or less than about 55% of the OD ofthe strain relief 182 section of the catheter body) distally oftransition 184. The catheter body distally of transition 184 may includeat least two or three zones of distinct flexibility. In a modified 3point bend test, a) a distal most zone will preferably exert betweenabout 6-10 gf when deflected 15 mm but less than 15 gf. An intermediateor mid shaft zone will preferably exert between about 10-20 gf whendeflected 15 mm but less than 30 gf, and a proximal zone will preferablyexert between about 30-60 gf when deflected 15 mm but less than 100 gf.Preferably, the catheter shaft will exert at least about 0.10 ozf-in atthe metallic insert junction when rotated 360 but less than 1 ozf-in.

The proximal zone may have a length within the range of from about850-1050 mm, and in some implementations from about 925 to about 975 mm.The intermediate zone may have a length within the range of from about150 mm to about 250 mm, from about 175 mm to about 225 mm, or about 190mm to about 210 mm. The distal zone may have a length within the rangeof from about 150 mm to about 250 mm, from about 180 mm to about 230 mm,or about 195 mm to about 220 mm.

Although the present invention has been described in terms of certainpreferred embodiments, it may be incorporated into other embodiments bypersons of skill in the art in view of the disclosure herein. The scopeof the invention is therefore not intended to be limited by the specificembodiments disclosed herein, but is intended to be defined by the fullscope of the following claims.

Further variations and additional details of the catheters disclosedherein are disclosed in the attached Appendix, any one or combination ofwhich may be combined with any of the features described above,depending upon the desired performance. The contents of the Appendix arehereby incorporated by reference in their entirety herein.

What is claimed is:
 1. A reentry catheter for crossing a vascularocclusion, comprising: an elongate flexible tubular body including aproximal end, a distal end, a side wall, and at least one lumenextending therethrough; and a reentry zone on the tubular body includingat least three opposing pairs of side wall exit apertures incommunication with the at least one lumen, each opposing pair of sidewall exit apertures positioned at the same axial location along thetubular body and rotationally offset from an adjacent opposing pair ofside wall exit apertures within a range of 10 degrees to about 60degrees, inclusive.
 2. The reentry catheter of claim 1, furthercomprising a reinforcing ring surrounding each side wall exit aperture.3. The reentry catheter of claim 2, wherein the reinforcing rings areconnected by a frame in the side wall.
 4. The reentry catheter of claim3, wherein a portion of the frame comprises a helical strut extendingbetween adjacent opposing pairs of side wall exit apertures.
 5. Thereentry catheter of claim 2, wherein the reinforcing rings comprise aradiopaque material.
 6. The reentry catheter of claim 1, furthercomprising an inflatable balloon on the tubular body, the inflatableballoon in communication with a second lumen extending axially throughthe tubular body.
 7. The reentry catheter of claim 1, further comprisinga guidewire lumen extending axially through the tubular body between aproximal port and a distal port.
 8. The reentry catheter of claim 7,wherein the proximal port is spaced distally from the proximal end ofthe tubular body.
 9. The reentry catheter of claim 7, wherein theproximal port is within about 20 cm of the distal end of the tubularbody.
 10. A reentry catheter for crossing a vascular occlusion,comprising: an elongate flexible tubular body including a proximal end,a distal end, a side wall, and a single lumen extending therethrough;and a reentry zone on the tubular body including a plurality of sidewall exit apertures, the side wall exit apertures in communication withthe single lumen and arranged in a spiral configuration along thetubular body such that any one side wall exit aperture is rotationallyoffset no more than 45 degrees from an adjacent proximal side wall exitaperture.
 11. The reentry catheter of claim 10, wherein the spiralconfiguration of the plurality of side wall exit apertures extends atleast 360 degrees around the tubular body.
 12. The reentry catheter ofclaim 11, wherein the spiral configuration of the plurality of side wallexit apertures includes at least five side wall exit apertures.
 13. Thereentry catheter of claim 10, wherein at least two of the plurality ofside wall exit apertures form an opposing pair of exit ports at the sameaxial location along the tubular body.
 14. The reentry catheter of claim10, further comprising a plurality of radiopaque markers, eachradiopaque marker at the same axial location along the tubular body asat least one side wall exit aperture.
 15. The reentry catheter of claim14, wherein the plurality of radiopaque markers includes radiopaquerings in the side wall of the tubular body, the radiopaque ringssurrounding the plurality of side wall exit apertures.
 16. The reentrycatheter of claim 15, wherein the plurality of radiopaque markers areconnected by a frame in the side wall.
 17. The reentry catheter of claim16, wherein the frame includes at least first, second, and third helicalstruts, each strut having a different helical pitch or orientation thanthe others.
 18. The reentry catheter of claim 10, wherein each of theplurality of side wall exit apertures has a major axis extendinglongitudinally along the tubular body and a minor axis extendingcircumferentially around the tubular body, the major axis having alength that is at least about 150% of a length of the minor axis. 19.The reentry catheter of claim 10, wherein each of the plurality of sidewall exit apertures includes a ramped surface that inclines radiallyinward into the aperture.